To compare effect of two different exogenous surfactants on neonatal mortality; compare effect of two different exogenous surfactants on the incidence and severity of acute RDS, air leak complications of RDS, and pulmonary hemorrhage; to compare the effect of two different exogenous surfactants on the incidence and severity of chronic lung disease and compare the effect of two different exogenous surfactants on the incidence of other RDS morbidities.